Showing papers by "Dnipropetrovsk National University of Railway Transport named after Academician V. Lazaryan published in 2020"

Effect of Vacuum Hot Pressing Temperature on the Mechanical and Tribological Properties of the Fe–Cu–Ni–Sn–VN Composites

Abstract: The mechanical (hardness and elastic modulus) and tribological (friction force and wear rate) properties of the Fe–Cu–Ni–Sn–VN composites produced by cold pressing and subsequent vacuum hot pressing at different temperatures are studied. The starting iron, copper, nickel, and tin powders have 5–50 μm particles and the vanadium nitride powder has 0.1–0.7 μm particles. When vacuum hot pressing temperature rises from 800 to 1000°C, the hardness increases from 3.75 to 5.37 GPa and the elastic modulus decreases from 176 to 125 GPa. As a result, the friction force reduces from 115 to 80 mN and the wear rate from 1.93 ∙ 10–5 to 0.45 ∙ 10–5 mm3 ∙ N–1 ∙ m–1. The factors promoting improvement of the mechanical and tribological properties of the sintered composites are discussed. In particular, the main factor improving the mechanical properties is that the grains are refined from 5–50 μm to 20–400 nm through the α → γ → α transformation when VN dissolves in α-Fe. In this case, the composite consists of a supersaturated solid solution of nitrogen and vanadium in α-iron, intermetallic Cu9NiSn3, and primary and secondary particulate vanadium nitride phases. A relationship between the structure and mechanical and tribological properties is established. The H/E and H3/E2 parameters that describe the elastic strain resistance and plastic strain resistance correlate with the wear resistance. The sintered composites are regarded as promising materials for developing a new generation of diamond-containing composites for stone processing industry.

Modelling of the Distribution of Return Traction Current Harmonics in Electrically Asymmetric Rails

Abstract: The distribution of return traction current harmonics in electrically asymmetric rails in AC feeder zone is considered. Modelling the traction current harmonics in rails allows to evaluate electromagnetic interference from rolling stock at an early stage and under the worst conditions for its safe operation. The return traction current that flows from rolling stock axles back to electrical supply substation is divided into two currents with different values in two rails due to their electrical asymmetry. The resulting differential traction current and voltage in two rails affect the railway signalling systems and can cause faults in track circuits operation. Rails as a path for return traction current are longitudinally non-uniform due to impedance bonds and track transformers connected to them. Modelling of non-uniform systems is usually carried out by presenting them in the form of series-connected multipoles, which correspond to track transformers and uniform traction lines between them. But such model is awkward and redundant for the problem under consideration due to the need to use excessive specific parameter values for all track circuits in the feeder zone. For the case of small rail asymmetry, the simplified model is proposed in the work. In accordance with it, the distribution of the total current of traction harmonic in two rails between train and traction substation is calculated. Then, using the asymmetry coefficients of the rails, the distributions of the differential current and voltage of harmonics in two rails between train and track transformer or between two track transformers are determined.

Improving the Reliability of Simulating the Operation of an Induction Motor in Solving the Technical and Economic Problem

Abstract: The article is devoted to the control of the statistical laws of linear voltages reproduced on a computer during computational studies on an energy-economic model when solving the problem of choosing protection tools for induction motors operating in workshop electric networks of industrial enterprises with low-quality electricity. Simultaneous and continuous estimation of average values, variances, autocorrelation and cross-correlation functions of harmonics of linear voltages is based on the adaptive approach.

Gondola cars dynamics from the action of longitudinal forces

Abstract: Purpose . The aim of the work is to study the influence of longitudinal quasistatic tensile and compressive forces in gondola cars arising at stationary and transient modes of train movement on their main dynamic indicators and interaction indicators of rolling stock with a rail track, taking into account the possibility of speed increasing. The relevance of this study is related with the need to control the longitudinal forces arising during stationary and transient modes of train movement, with increasing speeds, masses and lengths of trains, especially freight ones, increasing the locomotives` power. Methodology . The main method for studying the dynamic loading of a gondola car on typical three-element bogies is mathematical and computer modeling of the interaction of rolling stock and track structure based on the model of spatial vibrations of freight cars` couplings. In a theoretical study, the influence of quasistatic longitudinal tensile and compressive forces is considered depending on the change in speed and the force value on the tension of 1 MN; 0.5 MN; 0 and before compression of 0.5 MN; 1 MN. Findings . As a result of theoretical studies and after modeling, taking into account the processes of oscillation of gondola cars under the action of quasistatic longitudinal forces limited by norms to ± 1MN (100 tf), the dependencies of the main parameters normalized by technical documentation are obtained taking into account the value of the movement speed. Originality . The influence of longitudinal compressive and tensile forces on the dynamic loading of a freight car is studied in order to solve the problem of forecasting the dynamics of rolling stock, taking into account the value of the speed along curved track sections. Practical value . Application of the results obtained can increase the stability of freight rolling stock and the strength of the railway track, which in turn will remove some existing restrictions on permissible speeds and increase the technical speed of trains. The obtained dependencies of the main normalized indices on the longitudinal quasistatic force will make it possible to predict the development of deviations and prevent their transformation into the dangerous ones for train movement.

To the problem of train running safety

Abstract: The paper is presenting the procedure used for establishing the cause of the wagon derailment. To do this, the computer simulations and the computational software, developed in the Dnipro National University of Railway Transport (DIIT) were used. The level of longitudinal forces and the wagons dynamic performance have been evaluated using the mathematical models of longitudinal oscillations of a train and the spatial vibrations of wagons, in particular of tank wagons. As a result of modeling we obtained oscillograms of longitudinal forces in each inter-wagon connection, the dependence of the largest longitudinal forces on travel time and distance traveled, the distribution of the maximum longitudinal forces along the train length, the speed dependence on travel time and track coordinates. We also obtained the dynamic performance of wagons: the vertical dynamics coefficients of the axle-box and central suspension, the horizontal dynamics coefficients and the derailment stability coefficient. The influence of the movable load in the tank wagons and the characteristics of rail irregularities on the stability coefficient against wheel climbing onto the rail is also considered. The presented methodology was used to determine the cause of the tank wagon derailment in a non-homogenous freight train consisting of 50 wagon tanks on an existing track section of the Lithuanian railways. When simulating the train movement, it was assumed that the train was equipped with elastic-friction absorbing devices and air distributors, turned on to the average operation mode. As a result of numerical experiments, an assumption was made about the cause of the train derailment.

Study of the temperature field and the thermo-elastic state of the multilayer soil-steel structure

Abstract: The technology of renewal of metal corrugated structures allows efficient and economical reconstruction of existing reinforced concrete structures by the method of encapsulation. However, such structures can be exposed to adverse temperature effects that in combination with traffic loadings could influence the operational reliability of the structures. This article deals with the method of evaluation of the stress-strain state of a three-layer cylindrical structure. The technique is based on the thermo-elasticity theory. The study is performed in two steps: determining the temperature field of a structure, and then calculating the temperature stresses and deformations. As a result of calculations, it was established that the level of temperature field and stresses in a three-layer structure caused by the maximum and minimum ambient temperatures can reach a significant level.

The Mathematical Support of Machine Surfacing for the Railway Track

Abstract: The condition of a railway track is characterized by many indices, including its geometric shape, both in the horizontal and vertical planes. The purpose of this paper is to create a mathematical tool to ensure the operation of track machines for surfacing, tamping, and alignment, which are equipped with automation systems. The developed mathematical model will be integrated into the AS "Strela" software package which is currently installed on machines. Scientific approaches used in the mathematical model allowed to reduce the operation of machines in "window", to simplify the work of maintenance personnel, to create an information base of track parameters, to establish rational parameters of curves during surfacing.

Coefficient of stability against lift by longitudinal forces of freight cars in trains

Abstract: The paper is devoted to a theoretical study of the car movement stability when exposed to longitudinal forces of a quasistatic nature. The authors obtained the expressions for calculating the resistance coefficient of the car lift by the longitudinal compressive force acting on the car as part of a freight train. The influence of some factor's combination on the longitudinal forces, at which the car movement stability is still maintained, was analyzed using the analytical dependencies to assess the longitudinal loading of cars in trains. The study was carried out by analytical method for assessing the freight car stability when moving at different speeds along curved track sections. The calculations were made in a curve of small radius taking into account the inertia forces from the unbalanced acceleration. In a theoretical study, the influence of quasistatic longitudinal compressive forces depending on changes in speed and force value, as well as the influence of friction in the wheel flange and rail contact and the eccentricity of fastening the automatic coupler shank on the stability were considered. When applying the results obtained, the stability of freight rolling stock can be increased, which in turn will remove some existing restrictions on the permissible speeds and increase the technical speed of train movement. Using the described methodology for determining the lift resistance coefficient will make it possible to justify the cause of derailment, as well as to develop and put into practice technical measures to prevent the lift of carriages, thrusts and shears of the track.

Phenomena induced by UV irradiation in PbMoO4 single crystal

Abstract: Electrical properties and optical absorption of PbMoO4 single crystal were studied after UV irradiation. Anomalies of permittivity e and conductivity σ were detected and attributed to the dipole ce...

Multidisciplinary Nature of the Psycholinguistic Discourse Neuroeconomics

Abstract: Introduction. The article is devoted to the issues of multidisciplinary interaction in new scientific fields, which involve a wide variety of convergences, no matter how strange at first glance they may seem. One of these phenomena is the interaction of psycholinguistics and neuroeconomics. The goal. The article examines the transition of modern science to multidisciplinary discourse, which makes it necessary to conceptualize and possibly operationalize methods of psycholinguistics. The conceptualization of new areas of neuroeconomics, in a psycholinguistic context, presupposes a certain mental experience that includes, in addition to the processes of creating new concepts and contextual economic knowledge, also defining the role of interests, intentions, emotions in human economic activity. Methods. Multivariate analysis, comparative analysis, extrapolation. Results. It is proved that in recent decades the development of new areas of economic science, namely those related to the development of neuroeconomics, has significantly expanded the field of psycholinguistics. The production of new paradigms of economic theory, the formation of the corresponding definitions, objects requires the design and definition of them both in form and in content. It considers the need for a theoretical and orderly definition of the functional meaning of the psycholinguistic context of new definitions, the result of which can be a conceptual system for communication between specialists in various fields of science at the level of their professional understanding. It seems that the central issues in the psycholinguistic discourse of neuroeconomics have become the relationship between economics, psychology, linguistics and psycholinguistics. Such connection is undoubtedly of a multidisciplinary nature, which contributes to the deepening of the relationship between scientific thought, culture and language and became the impetus for understanding the nature of human cognition at a higher, multidisciplinary level of development of science. This is a necessary component for understanding the meanings and structure of concepts, terms and definitions, as well as communications at a higher scientific level. Conclusions. It is concluded that new areas of neuroeconomics such as behavioral economics, behavioral finance, emotional economics, psychological economics, have become areas of economic theory that, explicitly or implicitly, take into account the psychological characteristics of human perception and behavior in the process of economic activity. These definitions catalyze the theoretical integration of various scientific fields, and, above all, psycholinguistic science.

Computer simulation of biological wastewater treatment processes in aerotanks with plates

Abstract: Purpose. Efficiency determination of the aeration tank at the stage of design or reconstruction of bioreactors in which biological wastewater treatment is carried out requires the use of special mathematical models and calculation methods. The main purpose of the article is to develop CFD models for evaluating the operation efficiency of aeration tanks. Methodology. A numerical model has been developed for the computer calculation of the biological wastewater treatment process in aerotanks, taking into account hydrodynamics. The model is based on two-level mass conservation equations for the substrate and activated sludge and the velocity potential equation. The process of biological transformation of the substrate is calculated based on the Monod model. For the numerical integration of the mass transfer equations of activated sludge and substrate, the alternating-triangular difference splitting scheme is used. In this case, the basic equations are divided into two equations of a more simplified form. For the numerical integration of the equations for the velocity potential, it is split into two one-dimensional equations. Further, each equation is solved according to explicit scheme. For the numerical integration of equations that describe the process of substrate transformation based on the Monod model, the Euler method is used. Findings. The software implementation of the constructed numerical model has been carried out. The results of a computational experiment on the study of the wastewater treatment process in an aeration tank with plates are presented. This leads to the conclusion that the quality control of wastewater treatment in aeration tanks is possible with the help of plates. Originality. A multivariate CFD model has been developed, which makes it possible to quickly assess the efficiency of the aeration tank. A feature of the model is the ability to evaluate the operation of the aeration tank, taking into account its geometric shape and location of additional plates in the construction. Practical value. The constructed numerical model can be used during calculations in the case of designing aeration tanks, or in determining the efficiency of wastewater treatment under new operating conditions.

Detection of attacks on a computer network based on the use of neural networks complex

Abstract: Purpose. The article is aimed at the development of a methodology for detecting attacks on a computer network. To achieve this goal the following tasks were solved: to develop a methodology for detecting attacks on a computer network based on an ensemble of neural networks using normalized data from the open KDD Cup 99 database; when performing machine training to identify the optimal parameters of the neural network which will provide a sufficiently high level of reliability of detection of intrusions into the computer network. Methodology. As an architectural solution of the attack detection module, a two-level network system is proposed, based on an ensemble of five neural networks of the multilayer perceptron type. The first neural network to determine the category of attack class (DoS, R2L, U2R, Probe) or the fact that there was no attack; other neural networks – to detect the type of attack, if any (each of these four neural networks corresponds to one class of attack and is able to identify types that belong only to this class). Findings. The created software model was used to study the parameters of the neural network configuration 41–1–132–5, which determines the category of the attack class on the computer network. It is determined that the optimal training speed is 0.001. The ADAM algorithm proved to be the best for optimization. The ReLU function is the most suitable activation function for the hidden layer, and the hyperbolic tangent function – for the output layer activation function. Accuracy in test and validation samples was 92.86 % and 91.03 %, respectively. Originality. The developed software model, which uses the Python 3.5 programming language, the integrated development environment PyCharm 2016.3 and the Tensorflow 1.2 framework, makes it possible to detect all types of attacks of DoS, U2R, R2L, Probe classes. Practical value. Graphical dependencies of accuracy of neural networks at various parameters are received: speed of training; activation function; optimization algorithm. The optimal parameters of neural networks have been determined, which will ensure a sufficiently high level of reliability of intrusion detection into a computer network.

Human destructiveness in the existing practices of late modernism violence: positive and negative dimensions

Abstract: Purpose Research of the phenomenon of human destructiveness in the context of metaphysical images and violence practices of late Modernism Theoretical basis The problem is that the philosophical reflection of violence as objectified, realized destructiveness of man is usually contextual in nature and is on the periphery of understanding its external manifestations Accordingly, anthropological crisis remains behind the scenes, as evidenced by the devaluation of the humanistic potential of modern culture That is why one should turn the focus from the obvious, objectively conditioned incarnations of violence in the XXI century (armed conflicts, local wars, terrorist acts) to the internal factors that are in the realm of existential The departure from the consideration of violence as an abstract, faceless or ideologically colored evil allowed us to focus on man, his way of thinking, life and social orientations, feelings and internal contradictions, which find their expression in one or another form of destructiveness Originality Based on the works of M Scheler and E Fromm defining for philosophical anthropology and psychoanalysis, for the first time the conceptualization of positive and negative forms of manifestation of human destructiveness against the background of sociocultural transformations of late Modernism was carried out It has been proved that its ontological principles are rooted in specifically human existence and relations with other members of society, while anthropological ones are directly connected with the endless struggle of the life, the vital with the spirit in man Conclusions Violence is a tool and a product of man’s transition to more mature and complex forms of existence The interdependence of the violence and nonviolence practices ensures the progressive movement of humanity towards society humanization This progress is accompanied by a natural internal conflict of personality, which can be both progressive and regressive At the metaphysical level, destructiveness appears as a connection between the entropy of world existence as a whole and the instability of human existence itself, which is a complexly organized and open to the world system Self-transcendence as an anthropological prerequisite for human destructiveness has a dual nature and combines negative and positive characteristics, the content and significance of which were revealed in the study The authors are convinced that there is no other way to overcome the negative, malignant destructiveness, except for the incessant, daily gathering of life meanings around them and their development After all, the loss of such core structures of the existence as the meaning, purpose and value of life has become a truly global problem for the modern world Emphasis is placed on the need to keep in harmony the trinity of body-soul-spirit, which will allow a person in any social transformation to preserve and increase his integrity

Research of dynamic indicators and influence of different types of rolling stock on railway track

Abstract: The technical level of rolling stock of railway transport directly affects the economic indicators of the transport industry and the economy of the country as a whole, which leads to the need for improvement of the control, quantitative assessment of the dynamic loading o f rolling stock to ensure safe and reliable communication at the railways. Therefore, in the process of designing and operating the rolling stock the quantitative assessment of dynamic loadings is a relevant scientific and technical problem. The purpose of this work is to study the influence of different types of rolling stock, taking into account the speed of movement on their main dynamic indicators and indicators of interaction of track and rolling stock. The basis of the research is the method of mathematical and computer simulation of the dynamic loading of a freight car using the model of spatial variations of the coupling of five cars and a software complex developed in the branch research laboratory of dynamics and strength of rolling stock (BRL DSRS). Theoretical studies have been carried out under condition of movement of several types of freight cars: a gondola car of the model 12-532, a hopper car for coal transportation of the model 12-4034 and a flat car with a long cargo of the model 13-401 and typical bogies 18-100 with the speeds from 50 to 90 km/h in the curves with radii 350 and 600 m, with superelevation 130 and 120 mm, correspondingly.

3D Modeling of Biological Wastewater Treatment in Aeration Tank

Abstract: Purpose. The main purpose of the article is to develop a 3D CFD model for modeling the process of biological wastewater treatment in an aeration tank. Methodology. For mathematical modeling of the process of biological wastewater treatment in the reactor, taking into account the flow hydrodynamics, geometric shape of the aeration tank, convective-diffusion transfer of the substrate and activated sludge, a 3D CFD model was built. The model is based on the three-dimensional equation of motion of an ideal liquid and the equation of mass conservation for the substrate, activated sludge. The field of sewage flow rate in the aeration tank is calculated based on the velocity potential equation. The process of biological transformation of the substrate is calculated on the basis of the Monod model. The splitting scheme was used for numerical integration of the equations of convective-diffusion transfer of activated sludge and substrate. The splitting is carried out in such a way to take into account the transfer of substrate (activated sludge) in only one direction at each step of splitting. The calculation of the unknown value of the substrate (activated sludge) concentration is carried out according to an explicit scheme. The Richardson method is used to numerically integrate the three-dimensional equation for the velocity potential, and the unknown value of the velocity potential is calculated by an explicit formula. Euler's method is used for numerical integration of equations describing the process of substrate transformation and change in activated sludge concentration (Monod model). Findings. The software implementation of the constructed 3D CFD model is carried out. A description of the structure of the developed software package is provided. The results of a computer experiment to study the process of wastewater treatment in an aeration tank with additional elements are presented. Originality. A new multifactor 3D CFD model has been developed, which allows quick assessing the efficiency of biological treatment in an aeration tank. Practical value. The constructed 3D CFD model can be used to analyze the efficiency of the aeration tank under different operating conditions at the stage of sketch design of wastewater treatment systems.

Modern trends of logistics development on the railway market

Abstract: Інтеграція України до транспортної системи ЄС, функціонування міжнародних транспортних коридорів у Європі, зростання транспортних послуг зумовлюють необхідність виявлення низки проблем, пов'язаних із логістичними технологіями. Розвиток залізничної інфраструктури передбачає створення регіональних інформаційно-логістичних центрів, розгалуженої термінальної мережі, що має бути забезпечено шляхом формування інтегрованих систем управління логістичним транспортом. Наведено напрями формування ефективної транспортної логістики на залізничному транспорті, враховуючи велику і всеосяжну приватизацію, яка торкнеться залізниці. Щоб забезпечити приплив капіталу для проведення модернізації «Укрзалізниці», частину акцій держкомпанії необхідно продати іноземним інвесторам, необхідне широке впровадження державно-приватного партнерства, що допоможе створити прозору та ефективну модель бізнесу для залізничного транспорту і в кінцевому підсумку підвищить його конкурентоспроможність. Ключові слова: транспортна система, інтеграція, інфраструктура, логістика, ринок залізничних перевезень, державно-приватне партнерство.

Detecting of Signal Distortions in Cab Signalling System Using ANFIS and WPESE

Abstract: The problem considered in the work is concerned to detecting of signal distortions occurred in the railway ALSN cab signaling system. The ALSN system is designed to transmit track status information into the train cab and uses rails as a continuous communication channel between track and train. The amplitude and duration of the pulses in the ALSN code combinations are changed over time due to deterioration of the track transmitters and other devices in the signal transmission channel, as well as due to electromagnetic influence of the traction current, rails magnetization, and other sources of electromagnetic interference. Due to distortions of ALSN signals, their decoding becomes unstable, which leads to intermittent failures in the form of temporary incorrect indication at the cab traffic light or to complete failure of the ALSN system. Diagnostic of the ALSN system and the revealing of signals with distortions is carried out by analyzing the signal current, recorded using the railway car-laboratory. However, the use for this purpose of the classifiers with sharp boundaries for input diagnostic parameters and strict rules for signal selection does not allow us to reveal incipient defects that arise in the ALSN system. The work investigates the effectiveness of using adaptive neuro-fuzzy inference system (ANFIS) and wavelet packet energy Shannon entropy (WPESE) for timely detecting of signal distortions in the ALSN system. The obtained results confirmed the efficiency of ALSN signal processing using ANFIS and WPESE for detecting of railway sections with unstable or faulty ALSN system.

Emergency Burning of Solid Rocket Propellant: Damage Risk Assessment to People in the Workplace

Abstract: Purpose. This work includes the development of a computer model to calculate the risk of thermal damage to people in the shop in case of emergency burning of solid rocket propellant. Methodology. To calculate the temperature field in the shop in order to determine the zones of thermal damage to workers in the building, the equation expressing the law of energy conservation was used. Based on this modeling equation, the temperature field in the shop is calculated in the presence of a source of heat emission – burning solid rocket propellant. To calculate the velocity field of air flow in the shop, taking into account the location of obstacles in the path of heat wave propagation, we used the model of vortex-free air motion – the equation of the velocity potential. A two-step finite difference scheme of conditional approximation is used to numerically solve the equation for the velocity potential. A difference splitting scheme was used to numerically solve the energy equation. At the first stage of construction of the difference splitting scheme of the two-dimensional energy equation into the system of one-dimensional equations is performed. Each one-dimensional equation allows you to calculate the temperature change in one coordinate direction. The point-to-point computation scheme is used to determine the temperature. When conducting a computational experiment, the air exchange in the building is taken into account. The risk assessment of thermal damage to personnel in the building is performed for different probabilities of the place of emergency combustion of solid rocket propellant. Findings. Using numerical model prediction of the potential risk areas of thermal damage to staff in the shop for a variety of emergency situations was performed. Originality. A computer model for rapid assessment of the potential risk of damage to people in the shop in case of emergency burning of solid rocket propellant was constructed. Practical value. The authors developed a code that allows you to quickly simulate the temperature fields formation in the shop in case of emergency burning of solid rocket propellant and to identify potential areas of thermal damages to workers based on this information. The developed computer program can be used to assess the risk of thermal damage in the chemical industry in case of emergency.

Analysis of friction interaction andoptimisation of detail surface hardeningtechnologies using non-local mathematicalmodels

Abstract: Purpose: The aim of the work is to build physically sound engineering and design schemes that take into account the behaviour of polycrystalline metal systems under intense loads and allow optimization of surface treatment technologies to increase the operational reliability parameters of products. Design/methodology/approach: Using the approaches of thermodynamics, a methodological scheme is proposed, on the basis of which it is possible to optimize surface engineering technologies to increase the contact durability of details. Findings: It was found that the maximum increase in the durability of steel 40X13 (AISI 420) is achieved with thermocyclic ion nitriding in a cycle of ± 50°C, and the minimum with isothermal nitriding. Research limitations/implications: In this paper, the optimization of technological solutions to increase the contact durability of structural elements operating under prevailing power loads is given. Practical implications: Using the proposed mathematical relationships, optimal technological regimes of ion-plasma nitriding were established for various operating conditions, under which the maximum durability and wear resistance of 40X13 (AISI 420) steel are ensured. Originality/value: The paper proposes an approach to the formation of functionally gradient surface layers of steel with specified operational parameters when choosing optimal nitriding technology modes based on nonlocal mathematical models.

Constructive Modeling of the Software Development Process for Modern Code Review

Abstract: The preeminent point of this work is to construct a model of the software development process for automatic analysis. Utilizing constructive-synthesizing modeling (CSM) tools, a code-writing history constructor was proposed. This research provides an innovative method for code and development process review in the preparation of teaching programs. This work aims to encourage the use of code review and monitoring the coding practice in educational institutions. The standard approach to evaluation, which takes into consideration only the result, no longer complies with the modern specifications for teaching programming. Practically, it is supposed to be utilized in programming training, particularly in initial stages.

Research on Return Traction Current Harmonics

Abstract: The diagnostic tool of code current parameters and return traction current interferences is proposed. This apparatuses allows to analyze the spectrum and the value of interferences in the track circuits and to determine their sources. The research results are illustrated. The probability characteristics of return traction current interferences are determined.

Prediction of the stress-strain state of circular workings in a layered massif by scaling

Abstract: The scientific and technical task for determining the stress-strain state of mine workings is complicated by the presence of a layered massif. This task assumes particular importance in the case of circular tunneling. During its operation, it is important to predict the change of the stressstrain state for the massif or to carry out the prompt determination in the change of stresses and displacements for the unsupported working. The solution of this geomechanical task allows performing geometrical matching of the working, ensuring its strength and stability in the layered massif. A numerical finite element method based on StructureCAD (SCAD) software package was used to solve it. Four geomechanical systems were calculated: “unsupported working – layered massif”. Owing to the obtained results, graphs of stresses and displacements were constructed, which allow to determine these parameters for workings with different geometric parameters and X -parameter characterizing the ratio of the elasticity modulus of the matrix and the layer. Obtained regularities of change of stresses and displacements for the unsupported working when zooming made it possible to introduce scaling-parameters, which are a dimensionless ratio of the radii for a real system and a system with a unit diameter.

Electromagnetic Compatibility and Power Quality of Traction and Non-Traction Consumers

Abstract: The energy efficiency of power traction system and the power quality of the electric grid are estimated. The electromagnetic compatibility (EMC) traction and non-traction consumers are investigated. The propagation of traction current is studied as well as the third harmonic. The coefficient of harmonics is accorded the standards on the 110 kV buses.

Increased controllability of the distributed traction system in emergency mode

Abstract: The puprose of the work is to improve approaches to the controllability of power consumption in distributed power systems of electric rolling stock using modern technologies and equipment. Unequal energy consumption on the shoulders of the power supply causes additional losses in the system and makes the voltage mode worse on the current collectors of electric locomotives. To increase the controllability of operation modes, is proposed to use feeder volt-additional converters with arcless commutation of short-circuit currents. Using such converters allow to stabilize the voltage on the current collectors of electric locomotives and reduce the switching-off time. Variant calculations using the proposed circuit engineering of traction substations on the simulation model prove that the power losses from the equalizing currents are significantly reduced

Fryze Reactive Power in Electric Transport Systems with Stochastic Voltages and Currents

Abstract: The paper presents the theoretical foundations of reactive power and additional power losses in a direct current electric transport system. Numerical calculations of inactive power and losses in the circuits of electric DC locomotives and trams have been carried out. Discrepancy between the sign of the instantaneous power and the presence of exchange processes in non-linear circuits of electric transport systems with stochastic voltages and currents is discussed.

Asymmetric power supply circuit design for electric rolling stock on the electrified DC rail

Abstract: Modern requirements for the traction power supply system of direct current in providing the high-speed movement are reduced to the need of ensuring a normalized voltage level of 2900 V on current collectors of electric locomotives. At the same time, the power supply system has to be stable on changes in power consumption and have the necessary specific energy intensity. The purpose of the work is to explain the transition to a new circuit design of the traction network using additional generators of electric energy. The proposed asymmetrical power supply system of the electric rolling stock allows to provide the required voltage level on the electric locomotive current collectors, to reduce the range of its changes and to reduce the power losses by 14.3% compared to the symmetrical centralized power supply circuit design with passive boosting of the traction network.

Geotechnical analysis of optimal parameters for foundations interacting with loess area

Abstract: The article highlights results of the geotechnical analysis of the stress and strain state for the base of a subsoil massif under its interaction with the strip foundations. The massif is represented by loess soils which while soaking give overtime subsidences that complicate the operation of a building or a structure. Through geotechnical iterative research, optimization of the parameters for strip foundations on four axes at a four-storeyed residential building is carried out. Checks are performed on two groups of limiting states for scenarios of soil occurrence in natural, moistened and compacted states. The optimum dimensions in the width of strip foundations are selected, they give approximately the same strain values of the base after the creation of the soil bedding with its layer-bylayer compaction. The relevance of this research is to develop optimal parameters in the design of strip foundations for shallow depth on subsidental loess soils.

Formalization of an integrated approach to the formation and management of flexible associations of corporate structures

Abstract: Subject. The process of developing and researching the synthesis of a conceptual mathematical model for the formation and management of flexible unified corporate structures in an uncertain market environment. Purpose of work. Create and research a mathematical model for the formation and management of flexible integrated corporate structures in an uncertain market environment. Methodology of the work . The theory of bounded sets measurable in the Lebesgue theory for the formation and management of organizational business structures. Result of work. A conceptual mathematical model is developed for the formation and management of flexible unified corporate structures in an uncertain market environment, and the results of development and calculations are presented. Scope. It is used in the development of projects for the formation and managing combined corporate structures in an uncertain market environment for regulatory and flexible business areas. Conclusion . Created a conceptual mathematical model for the formation and management of flexible unified corporate structures in an uncertain market environment.

Numerical model to simulate ventilation of dead-end mine working with brattice

Abstract: A computational model to simulate ventilation of a dead-end mine working with line brattice has been developed. To solve fluid dynamics problem, i.e. to compute flow pattern, model of inviscid flow has been used. That allows to compute quickly air flow pattern. To simulate dust dispersion in the dead-end mine working with brattice twodimensional equation of mass transfer has been used. Numerical integration of Laplas equation for the velocity potential has been carried out using Samarski two steps difference scheme of splitting. Proposed CFD model allows quick computing of dust dispersion in the dead-end mine working with brattice. Markers (porosity technique) have been used to create the complex geometrical form of computational domain. Results of numerical experiments which had been performed on the basis of the developed CFD model have been presented.